To contribute to a better understanding of second language (L2) sentence processing, the present study examines how L2 learners parse temporarily ambiguous sentences containing relative clauses. Results are reported from both off-line and on-line experiments with three groups of advanced learners of Greek whose native languages (L1s) were Spanish, German, or Russian as well as from corresponding experiments with a control group of adult native speakers of Greek. We found that, despite their nativelike mastery of the construction under investigation, the L2 learners showed relative-clause attachment preferences that were different from those of the native speakers. Moreover, the L2 learners did not exhibit L1-based preferences in their L2 Greek, as might be expected if they were directly influenced by L1 attachment preferences. We suggest that L2 learners integrate information relevant for parsing differently from native speakers, with the L2 learners relying more on lexical cues than the native speakers and less on purely structurally based parsing strategies.